With a signal recovery transducer, such as for example an optical pick-up, recording media can be read and/or information can be stored on recording media, the quality and quantity of the recording or playback being influenced significantly by the recording medium itself. To compensate for adverse effects of the recording medium during recording and/or playback, a pick-up with adaptation is provided. The recording medium may be an optical recording medium or another type of recording medium in a corresponding recording and/or playback machine. In the case of an optical recording medium, data or information can be stored in so-called pits in, for example, a compact disc (CD) and/or magneto-optical domains in the case of a magneto-optical disc (MOD) or a ROM-RAM or in some other way.
It is generally known that recording media, such as for example optical recording media, have different reflection properties, due to the manner in which they are manufactured, caused by aging or soiling. Since the recording medium is to be regarded as a component part of the machine during the recording or playback of information, both its properties and the properties of the machine influence the quality and quantity of the information recorded and/or played back. This influencing relates in particular to the properties of closed-loop control circuits. If, for example, a different recording medium is loaded into the optical pick-up or if changes occur with regard to the laser power, the amplitude of the signal reflected by the recording or information medium changes and, as a result, the loop gain of control circuits changes. This may have the result that, with excessive loop gain, the stability of the control circuit is lost or, if the control gain is inadequate, the system deviation becomes too great to ensure reliable functioning of the machine during recording and/or playback.
It is therefore the object of the invention to avoid these disadvantages of pick-ups, which consist in particular of the influence on the control loop gain in closed-loop control circuits of the pick-up due to the recording medium.